Process for the manufacturing of heating elements for thermic telephones.



,P. DE LA NGE & R. A. BARON VAN LYNDEN.

PROCESS-FOR HE MANUFACTURE OF HEATING ELEMENTS FQR THERMIC TELEFHONES. APPLICATION FILED N-0V.'4. 1915.

Patented Nov. 13, 1917.

Robert flernzgt EH01: r1): Z azdeJz PIETER DE LANGE Ann no annr asaaom Barton. Vanessa; or YLANZPS, ASSIGNORS 'ronA MLoozn vnnnoorsorrnr nn annaa a s n nama rnrlnrnooiv namsenrrrr for U'rnEcHT, NETHERLANns, AoonroRA'r'Ioiv or PROCESS FOR THE MANUFACTURE or amiaemamms FORTI-IERIVIIC TELEPHONES.

Specification of Letters Patent.

Application filed November 4, 1915. Serial No. 59,624.

To all whom it may concern: 7 I

Be it known that we, Prn'rnn on LANGE and ROBERT AnRNoUtr BARON VAN LYNDEN, both subjects of the Queen of the Netherlands, and residing at Utrecht, in the Netherlands, have invented a new and useful Process for the Manufacture of Heating Elements for Thermic Telephones, of which the followingis a specification.

Our invention relates to a process for the manufacture of heating elements for thermic telephones from Wollastone wires, and has for its object to arrange as many arche shaped wires as possible on a heating conductor support of a given size, as is required for insuring a favorable sound eifect.

Accordin to this invention, this is accomplished y the adjoining branches of the arch-shaped lVollastone wires being embedded close together in recesses of the heating conductor support made ofinsulating material, and then subjected in the Well known manner to etching at their portions projecting from the support.

In this way it is possible to obtain an exceedingly close or compact arrangement of the arch-shaped heating wires to be formed into a heating conductor, as themethod of embedding the wires in the support insures that the feet or bases of the adjoining heating wires-which project from the support to an'extent equal to the length of the sound producer-are at a very small distance from each ,other, viz: a distance equal to the double thickness of their coating. If, for instance, Wollastonewires 0.48 mm. in diameter are used, the'platinum core of which is only 0.005 mm. in diameter, the cores of the wires will have a distance apart of 0.47 5 mm. if the wires are .so placed that they are in contact with each other at their bases. I

Reference is to be had to the accompanying drawings, in which two forms of heatlng elements manufactured according to thepresent process are shown by way of example onv an enlarged scale, Figure 1 being a perspective view (with parts in section) of one form, and Fig. 2 a sectional vlew of the other form.

In the heating element shown in Fig. 1,

l is the heating conductor support of insulatlng material, for instance vulcanized rubber or ebonite. On the upper surface'of the support 1 are provided recesses 2 in which the branches 3 of'the arch-shaped heating wlres jolned together below inthe form of loops, are secured in such a. manner that Patented Nov. 13,1917.

the adjoining branches are quite close together. The portion 4: of the heating wires, pro ecting from the support 1 and correspondlng to the desired length of sound producer, is then subjected in the wellknown manner to etching, whereby the fine plati' num cores are exposed. It'follows that these cores, .at their bases 6, are at a distance equal to double the thickness of the wire coating, whereby partial short circuits be tween the platinum wires are rendered impossible.

In practice, the arches 4"arefnot etched quite down to their support'l but a portion of their coating is left at the bases 6 so thatthe acid is not drawn into the embedded portion 3 by capillary action.

In the modification illustrated in Fig. 2

the heating wires are not continuous but formed of separate loops 10 the branches? of which are embedded close together in re' cesses 8 of a support 7. Those branches 11 which are at the outside of 'theyconductor, are carried through perforations 12 in the same. The etching of the heating wire loops is effected in the manner above described.

Weclaim: V

1. The process for the manufacture of heating elements for V thermic telephones from Wollastone wires, consisting in embed ding the ends of adjoining loops contigu ously in recesses of a support, and etching the looped portions for the desired sound producer length.

2. The process for the manufacture of heating elements for; thermic telephonesfrom Wollastone wires, consisting in bending a continuous wire to form a plurality of arches and doubled up bends, embedding saidbends in recesses of the heating conductor support with the members of the bends in mutual contact, and etching said for the manufacture of heating elements for thermic telephones leaving unetched a portion of the Wires at from Wallastone W res, consisting in 6111- the face of the support.

beddingthe ends of adjoining loops in con- In testimony whereof We have signed this tact With each other, Within recesses of a specification.

support, and etching the looped portions Q 'PIETER DE LANGE. for the desired sound producer length and ROBERT AERNOUT BARON VAN LYNDEN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

7 a Washington, D. G. 

